The present invention relates to well treatment fluids and methods utilizing nano-particles and, in certain embodiments, to well cement compositions and methods utilizing nano-hydraulic cement.
In general, well treatments include a wide variety of methods that may be performed in oil, gas, geothermal and/or water wells, such as drilling, completion and workover methods. The drilling, completion and workover methods may include, but are not limited to, drilling, fracturing, acidizing, logging, cementing, gravel packing, perforating and conformance methods. Many of these well treatments are designed to enhance and/or facilitate the recovery of desirable fluids from a subterranean well. Examples of such well treatments are discussed hereinbelow.
In cementing methods, such as well construction and remedial cementing, well cement compositions are commonly utilized. For example, in subterranean well construction, a pipe string (e.g., casing and liners) may be run into a well bore and cemented in place using a cement composition. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the well bore and the exterior surface of the pipe string disposed therein. The cement composition sets in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement that supports and positions the pipe string in the well bore and bonds the exterior surface of the pipe string to the subterranean formation. Among other things, the annular sheath of set cement surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string from corrosion. Cement compositions also may be used in remedial cementing methods, such as squeeze cementing, repairing casing strings and the placement of cement plugs. In some instances, cement compositions may be used to change the direction of the well bore, for example, by drilling a pilot hole in a hardened mass of cement, commonly referred to as a “kickoff plug,” placed in the well bore.
Hydraulic fracturing is a process commonly used to increase the flow of desirable fluids, such as oil and gas, from a portion of a subterranean formation. Hydraulic fracturing operations generally involve introducing a fracturing fluid into a subterranean formation at or above a pressure sufficient to create or enhance one or more fractures in the formation. Enhancing a fracture includes enlarging a pre-existing fracture in the formation. The fracturing fluid may comprise particulates, often referred to as “proppant” that are deposited in the fractures. The proppant functions to prevent the fractures from fully closing upon the release of pressure, forming conductive channels through which fluids may flow to (or from) the well bore.
Another process that involves the use of particulates is gravel packing. A “gravel pack” is a term commonly used to refer to a volume of particulate materials (such as sand) placed into a well bore to at least partially reduce the migration of unconsolidated formation particulates into the well bore. Gravel packing operations commonly involve placing a gravel pack screen in the well bore neighboring a desired portion of the subterranean formation, and packing the surrounding annulus between the screen and the subterranean formation with particulate materials that are sized to prevent and inhibit the passage of formation solids through the gravel pack with produced fluids. In some instances, a screenless gravel packing operation may be performed.